"Early in 2011, Haber, his colleague physicist Earl Cornell and Peter Alyea, a digital conversion specialist at the Library of Congress, began analyzing the Volta Lab discs, unlocking sound inaccessible for more than a century. Muffled voices could be detected reciting Hamlet’s soliloquy, sequences of numbers and “Mary Had a Little Lamb.”

Remarkable. The YouTube video of the recording at Wired doesn't include Hamlet but I'll keep my ear out.